Objectives: The risk of subsequent fractures is double the risk of having a first fracture. We analysed whether this risk is constant or not over time.
Methods: A population-based study in 4140 postmenopausal women, aged between 50 and 90 years, on radiographic confirmed clinical fractures from menopause onwards analysed by Cox regression.
Results: 924 (22%) women had a first fracture and 234 (26% of 924) a subsequent fracture. Four percent of all first fractures occurred in each year from menopause onwards, while after a first fracture, 23% of all subsequent fractures occurred within one year and 54% within five years. When calculated from time of a first fracture, the relative risk (RR) of subsequent fracture was 2.1 (95% confidence interval (CI): 1.7-2.6) and remained increased during 15 years. When calculated for specific time intervals after a first fracture, the RR was 5.3 (CI: 4.0-6.6) within one year, 2.8 (CI: 2.0-3.6) within 2-5 years, 1.4 (1.0-1.8) within 6-10 years and 0.41 (CI: 0.29 -0.53) after >10 years.
Conclusions: From menopause onwards, clinical fractures cluster in time indicating the need for early action to prevent subsequent fractures.